Very high frequency tuner



R. c. CARLSON VERY HIGH FREQUENCY TUNER Jan. 13, 1959 4 Sheets-Sheet 1 Filed Feb. 23, 1954 INVENTOR. arr am c. mam/v Jan- 1 1 9 R. c CARLSON VERY HIGH FREQUENCY TUNER 4 Sheets-Sheet 2 Filed Feb. 23, 1954 INVENTOR. 205N C 64ESON Jan. 13, 1959 R. c. CARLSON 2,868,982

VERY HIGH FREQUENCY TUNER Filed Feb. 23, 1954 v 4 Sheets-Sheet 3 4/ '5 63 98 V l0 7 95 32 9/ I26 INVENTOR. REUBEN C. (421.50 39 74 13 W m ATTOKIVEY Jan. 13, 1959 R. c. CARLSON VERY HIGH FREQUENCY TUNER 4 Sheets-Sheet 4 Filed Feb. 25, 1954 Mm EL 50 N 7 A EfbBf/V C.

its coil holding elements United States Patent OfiFice 2,868,982 Patented Jan. 13, 1959 2,868,982 VERY HIGH FREQUENCY TUNER Reuben C. Carlson,

River Grove, Ill., assignor'to Admiral Corporation,

Chicago, Ill., a corporation of Delaware Application February 23, 1954, Serial No. 411,718 13 Claims. (Cl. 250-40) the space requirement by endeavoring to reduce the physical size of sub chassis assemblies and by grouping various components more closely together; the result of which is an profound decrease in the efficiency of reception, and a concurrent increase in the difiiculties arising out of construction and maintenance.

By the proposed invention it is realized that an efiicient novel construction of a V. H. F. tuner is accomplished proposed invention, and a more ascertainable understanding thereof will be obtained by referring to the drawings of which:

Fig. 1 is a side elevational view of a tuner with the shield cover removed, to show the interior construction:

Fig. 2 is a top plan view with the tubes and a shield cover broken away to show the structure underneath.

Fig. 2a is a fragmentary section of the top of the chassis with the cover in place.

Fig. 2b is a top plan View of the cover plate.

Fig. 3 is a side elevational view of the rotor shaft and removed from the assembly.

Fig. 4 is an end view of the end coil holding plate, taken from the line 4-4 of Fig. 3.

Fig. 5 is a similar view of the center coil taken from the line 5-5 of Fig. 3.

Fig. 6 is a similar view of the end supporting plate taken from the line 6-6 of Fig. 3.

Fig. 7 is a view of the rotor and a coil strip showing the coil strip partially inserted in position.

Fig. 8 is a side elevational view of acoil strip with the coils attached thereto.

Fig. 9 is a side elevational view of a modified form spring and coil strip support.

Figs. 10 and 11 are bottom and top views of stationary contact blocks removed from the assembly.

Fig. 12 is a view through the rotor, showing one of the coil strips in place and'in contact with one of the fixed contacts.

Fig. 13 is a similar view, but showing a modified form of contacts.

Fig. 13a is a section on the line 13a13a of Fig. 7.

Fig. 14 is an enlarged elevational view of a contact removed from the assembly.

Fig. 15 is a side view of the rotor and the frame with all the other parts removed to show how the rotor is supported in the frame. t

Figs. 16, 17 and 18 are views taken from the lines support plate 2 1616, 1717 and 18-18 respectively of Fig; l, illustrating portions of the wiring and other components.

Fig. 16a is a view taken on line 16a-16a of Fig. 1 showing the indexing plate and spring mechanism.

Referring now to the drawings in which like elements are designated by like reference characters, the numeral 3 (Fig. 1) indicates the metallic chassis which takes the form of a boxlike structure being substantially rectangular in shape and open on the bottom and the two longitudinal sides. End wall plates 5 extend vertically downward from the base 4 of the chassis while narrow strips 6 extend along the length of the longitudinal side of said rectangular base.

A shield plate 7 divides the base into two parts or zones and shields the signal input portion of the tuner from the oscillator and mixer portion contained within the respective zones. versely across most of the base, and then near one side thereof as shown in Fig. 2, the plate is bent away from the transverse portion (Fig. 17) to allow the about its pivotal axis. The construction of assembly will be explained in detail hereinafter.

Two tube receptacles 12, 13 of the bottom type variety are mounted on the upper surface of the base and extend into the box-like structure where the necessary circuitry is attached thereto.

A rectangular opening or shallow well (Figs. 2 and 17) is made in the base, the sides of which extend downward into the structure a slight distance to provide side walls 15 and 15' which terminate in inwardly extending horizontal ledges 16.

A fixed contact block assembly 17 is mounted on the underside of the two horizontal ledges and has stationary contacting surfaces 19 facing toward the rotor assembly 30. A second fixed contact block assembly 18 (Fig. 18) is also mounted on the horizontal ledges so that its contacting surfaces 19 face toward the rotor assembly. Since the block assemblies 17 and 18 are similar it is only necessary to explain in detail the characteristics of one.

The fixed contact block constructed from a suitable nonconductive material is rectangular in form and has a plurality of rectangular slots 23 (Figs. 10 and 11) cut out of the central portion. A small hole 24 and a narrow or 18 may take the form shown in Figs. 12 and 14. Each such contact is in the form of a thin metallic contact strip 19, one end of which presents an irregular curved loop 27 and the opposite end of which is a vertical portion 26 that provides a solder lug extending from the inner end of said loop. The loop is positioned within the rectangular slot 23 in the block 18, while the vertical lug portion 2-6 extends into and up through the adjacent narrow slot 25. At the lower end of its vertical lug 26 the contact strip of Figs. 12 and 14 is bent over downward and outward away from its loop27 to provide a lug 28 which extends just below the insulation block 18. The return leg of the lug extends upward and inward toward the loop to the loop through a flat segment 28a. A small hole is punched out of the contact strip at its flat segment 28a and when the strip is placed within the is directly over the hole 24 located on the block. A rivet 29 (Fig. 12) is placed through the above holes thereby securing said strip to said block. The lower side 27' (Fig. 14) of the loop 27 of each strip extends downward from the block and is in the rotatable path of the contacts in this rotor assembly. It is therefore realized that said contact strip has a cantilever type of motion when pres.

The shield plate extends trans-" and isolates the RF input to the mixer stage from the oscillator input to the mixer. The 1 vertical edge of the plate is cut out in the form of an arc' rotor assembly 30 to rotate freely the rotor block this hole aseassa sure is exerted on said strip by the rotor contact assembly 30 said pressure being of suflicient magnitude to assure a highly positive contact with the movable contacts of the rotor.

If desired, the lower lug on the contact strip may be omitted, in which case the lower end of the vertical lug 26 is joined directly to the flat strip portion 28a. Such a contact structure is shown at 1% in Figs. 17 and 18.

Alternatively, the contact structure may take the form shown in Fig. 13. Here the contact strip is similar to that of Figs. 17 and 18, except that it has a protruding lip 27b at the outer end of loop 27 which rests on an inwardly projecting, upwardly facing shoulder 1&1 form on the insulation support block 18.

A rectangular extension 10 (Fig. 2) of the center shield plate 7 shields block 17 from block is thereby preventing any interference between the input portion and oscillator portion.

The index plate 43 (Fig. 4) is provided with a plurality of openings 60 in radially spaced relation to each other, which openings are adapted to support the ends of the coil strip, being rectangular and having an enlargement 60a through which a tool may be inserted for adjusting the tuning slugs for the coils. The periphery of the plate is provided with regularly spaced hills and valleys 61 and 62 arranged to be engaged by an index roller 67 to hold the rotor in predetermined indexed positions, in the manner shown in Fig. 16a.

The valleys or indentations 62 are arranged to be engaged by a roller 67 which is carried by a spring arm 68. The arm 68 extends through a slot in the upper base of the chassis, is bent over at 69 and secured by a screw 7% threaded intothe base.

The center or guide plate 42 (Figs. 5 and 7) is provided with plurality of radially disposed slots 63 in align ment with the openings il for supporting the coil strips in their center portions. This plate also acts as a shield between the two sections of the rotor, shielding the R. F. section from the mixer and oscillator section. It has a smooth exterior surface, except for the interruptions by the notches adapted to engage with or ride on a grounding strip 64. As can best be seen in Fig. 17 the grounding strip is secured to a lug 65 on the shield plate 7 at one end and to the wall 15 of the well at the other end. Preferably it is staked and soldered at these points. The grounding strip may be curved to conform to the periphcry of the plate and is provided with a centrally disposed U-shaped bight as the walls of which may move apart to provide greater resiliency to the strip, as well as to help it conform to the surface of the plate 42, and to hold it in good contact therewith.

As previously stated the fixed contact blocks are secured to the ledges in. This is effected by providing the blocks with shoulders or flanges 2% (Fig. 12) whose inner edges 21 abut the edge of the ledge 16, which ledge I has tongues 22 (Figs. 17 and 18) that are struck from the ledge and which engage with the bottom side of the block.

It should be particularly noted, as best shown in Figs. 1618, that the opening 14 is not centered relative to the mid-point of the chassis and that the outer wall 15 is longer than the innermost wall. This results in a space savings, because it allows the tubes and their sockets to be mounted to one side of the rotor and permits short direct connection to be made between the sockets and the fixed contacts. Providing one wall longer than the other also tilts the fixed contact blocks so that a median line transversely through the block is normal to a diameter through the rotor thus assisting in a more accurate contact of the fixed contacts with the movable contacts of the rotor.

The shape of the fixed contacts With the lugs 26 and 29, one of which extends above the block and the other below (Fig. 12), facilitates connections to either the top or the bottom. The deeper side wall 15' also provides more space for the reception of leads through insulators 11 (Fig. 17) which enable connections to readily be made to the upper contact lugs 26.

The fixed contact blocks with their contacts are thus disposed in a well which is readily accessible from the top for the purpose of installing the circuit components as well as providing access to them for inspection, testing or repair purposes.

The well is closed by a cover plate, Figs. 2, 2a and 2b,

which acts as a shield as Well as a dust cover and also provides a means for securing the antenna lead transmission line 37 against strain on the components to which it is connected.

It includes a flat body part 31 of rectangular formation and is provided with sides 32 which terminate in tongues 33 and flanges 34. An end flange 35 is provided and it is adapted to extend under the top chassis Wall 4. The tongues 33 engage with the sidewalls 15 and 15' of the wells 14 while the other flanges 34 rest on the chassis top wall 4. Thus thetongues hold the same in alignment as well as in electrical conducting contact with the side while the flanges hold it above the opening. Certain of the flanges are provided with openings for the reception of screws 34 that may be threaded into threaded openings in the top wall to hold the same in position.

' As previously stated the cover also secures the lead in or transmission line,-relieving strains on the solder lugs and holding it in a fixed position. As can be seen from Fig. 2, the ends of the transmission line 37 are secured to the lugs 26 of the fixed contacts. The line is then dressed over the opposite side of the well. The cover side 32 has a short, downwardly depending lug 36 which, when the cover is in place, presses into the material of the line, between the wires and holds it securely in place. As can be seen the sides adjacent the lug are cut away so that there is no possibility of the edge cutting the line at the conductors and the capacity to ground is reduced.

The rotor assembly is journalled in the end walls of the chassis housing and carries a plurality of coil strips, each of which is arranged to enable reception of a television channel, and which may be selectively rotated into electrical contact with the fixed contacts.

The rotor includes a shaft 46 (Fig; 15), to one end of which is secured a strip retainer spring 41. Spaced from this spring is a center guide plate 42 which is also secured to the shaft. A third member, the index plate.

43 is also secured to the shaft spaced from the center guide plate.

The end of the shaft projects slightly beyond the strip retainer spring and is of reduced cross section at 44, arranged to be rotatably journalled in the end plate of the chassis. The journal for the other end of the rotor, and which enables the rotor to be quickly assembled or disassembled from the chassis, comprises a bushing 46, with an internal bore of the same diameter and adapted to fit snugly over the shaft. The body of the bushing is of a size to fit snugly in an enlarged part of a keyhole shaped slot 47 (Fig. 16) in the end wall of its housing. The end of the bushing is provided with a head or flange 48 forengagernent with the outer face of the end plate and the bushing is held in position by a wire spring member 49 having one end secured to a rivet 50 on the end Wall and the other end extending through a hole 51. The extremity of the spring is bent over to prevent it from accidental removal. The position of the rivet and hole are such that the body of the spring presses toward and engages the bushing, and enters into a tangential slot 46a in the bushing 46.

The wire retainer spring being in the slot holds the bushing against removal. At the same time in order to remove the bushing it is merely necessary to rotate it a part turn, at which time its slot 46a is rotated out of contact with the Wire 49 which rides up on the unslotted part of the bushing and the bushing may then be moved axially on the shaft out of the large part of the keyhole slot 47 in the chassis end wall 5 and then'the shaft 40 lowered through the narrow part of slot 47 and the entire rotor thus removed from the chassis.

The shaft 40 extends beyond the index plate 43 and is provided, with a squared end 52 (Fig. 1) for the reception of a control knob, not shown. It also provides a bearing surface for a tubular shaft 53 which provides the so-called fine tuning control. One end of this shaft carries a dielectric member 54 (Fig. 16) in the form of a hyperboloid. which when rotated inserts the dielectric in varying degrees between a plate 59, that is secured to the outer end of the chassis in spaced relation thereto, and the end of a condenser plate (ungrounded) which may comprise a ceramic member 55 having a conductive coating 56 on the outer surface and which is connected to a lead 56 extending through a hole in the ceramic in a. manner well known. in the art. A spring washer 57 (Fig. 1) between the end of the tubular shaft and the bushing 46 pushes the plate 54 back against a dimple 58against which the plate rides and thus maintains a constant position. The grounded plate 59 and the outer conductive surface 56 provide an air dielectric condenser and the capacity is changed by the insertion of the dielectric plate therebetween.

The strip retainer spring 41 (Fig. 6) ismade of highly resilient material and includes a center body portion 72 riveted to a hub 73 that is carried by the shaft. The periphery is provided with radial slots 74 which separate it into fingers 76 each of which carries a rectangular opening 75. i i V The assembly of the rotor just described is adapted to old the tuning coil strips and to enable them to be selectively rotated intoengagement with the contacts carried by the fixed contact blocks. To this end the coil strips, Fig. 7, each comprise an elongated rectangular frame 80 one end of which is provided with a projecting lug 81 of rectangularformation arranged to seat snugly A in one of the openings 60 of the index plate. Near the center the strip is formedwith a cross section at 82 similar to the strip which is adaptedto slip into and be guided by the walls of the slot63. The other end is provided witha rectangular lug 83 for engagement in the opening 75 of the retainer spring 41. As can best be seen in Fig. 7 the end 81 is first slipped into the opening 60 of the index plate, the spring finger 76 moved outward and then the strip moved downward until the lug 83 snaps into the opening 75.

As best shown in Fig. 9 the fingers 76 may be bent outward at their periphery 76' to facilitate the insertion of the strip.

Each coil strip is openings 86 and 87 and which separate provided with a pair of rectangular extending longitudinally of the strip it into upper and lower bars 88 and 89. The upper bar supports the coil contacts and to that end it is provided with notches 91 on the side defining one side of the opening. At the outer edge of the strip and spaced oppositely to the tongues formed by the notches 91 are lugs or projections 92. The notches and lugs provide means for maintaining accurate alignment of the contacts, longitudinally of the strip which contacts are secured to the upper bar 88.

In the embodiment shown, it will be noted that the opening 86 is shorter than the corresponding opening 87. This enables more contacts to be placed on one of the upper bars which is usually the case when the shorter portion is connected to the R. F. and the longer to the oscillator mixer circuit.

The contacts each comprise a strip of metal which is wrapped around the upper bar between the lugs 92 (Fig. 8) and in the notches 91 with the ends being brought together and crimped to each other to provide lugs 95 which also serve as solder lugs. This is effected by providing 54 of a different dielectric constant a notch in the upper extending part 96 and a tongue 9'7 on the lower extending part which seen in Fig. 13a. At the upper end of the metal strip a raised boss 98 is provided by deforming the metal, this being the actual point'of contact with the hired contacts. At the lower corner, on the same side as the lug 92, the strip is provided with a semi-circular bight 99 which extends away from the corner. Inasmuch as the strip is made of resilient metal this construction assures that a firm gripping action is had by the strip with the bar throughout the life of the switch. I

At the extremities of the coil strip adjacent the ends of the openings 86 and 87 (Fig. 8) the strip is: made thicker and provided with semi-circular recesses 100. In the mid portion between the two openings similar bosses are provided having openings 101.

These recesses 100 and 101 form seats for the coil forms 102 upon which the coils 103 are wound the ends of which are connected by soldering to the lugs 92.

As best can be seen in Fig. 8 the one coil. form, which is a fiber tube, is provided with a slot 105 used to adjust the tuning of the oscillator are more accessible. The coil strips, although smaller, are much more rigid asuring a better contact over a larger period of time.

Having thus described my invention 1 am aware that numerous and extensive departures may be made there from without departing from the spirit of the invention as defined in the appended claims.

I claim:

1. A V. H. F. tuner having a chassis forming a cradle for supporting a rotor member, said rotor member being 2. A V. H. F. tuner having a chassis forming a cradle for supporting a rotor member, contact blocks secured to the chassis and carying member rotatably mounted is bent over as best it may engage the threads of an adjusting.

aseense and a somewhat larger radial portion and openings extending longitudinally in each contact block thereby form ing on each contact block transverse end members, outer and inner longitudinal side members and a central bridging member which connects the side members arcuate slots formed in said transverse end members and central bridging member, a plurality of indentations formed on each outer longitudinal side member, contacting surfaces secured to each outer longitudinal side member and residing in said indentations, tubular members having inductance members disposed about the circumferential surface of said tubular members, said tubular members being received in said openings in said contact blocks, said arcuate slots providing seats for the ends of said tubular members, said inductance members having connections to said contacting surfaces, said contacting surfaces of said rotor member being positioned to engage the fixed contacts on the contact blocks secured to said chassis when said rotor member is rotated to selectable positions and thereby connecting said inductance members electrically to the circuitry connected to said fixed contacts on said chassis contact blocks.

3. A tuner of the class described including a frame having spaced end walls, one of said end walls being formed with a circular opening defining a bearing surface, the other opposite end wall having a slot entering from the edge of the wall and terminating in an enlarged circular opening in coaxial alignment with said first opening, a rotor for said tuner including a central shaft, said shaft having a reduced diameter end journaled in said circular opening in said one end wall, a bushing sleeve mounted in the other end wall and having a bore which receives said shaft and provides a bearing surface for said shaft, said bushing sleeve having a body snugly received in said circular opening in said other end wall, said slot in said other end wall being wider than said shaft, said bushing sleeve having an enlarged head which engages the outer surface of said other end wall and having a transverse slot in its periphery spaced from the head and juxtaposed to the inner surface of said other end wall when the head is in engagement with the outer wall, and lock means disposed on the. inner wall and engaging in said transverse slot in the bushing sleeve to lock said bushing sleeve in place.

4. A tuner of the class described including a box like chassis having end walls and a top wall, a rotor rotatably mounted in said end walls and carrying tuner strips rotatable below the top wall and having contacts thereon, said top wall being formed with a shallow well disposed above said rotor and fixed contact carrying members secured in the bottom of said well and having fixed contacts arranged for engagement with the contacts on said rotor strips, means for closing said top well comprising a cover having portions entering into and engaging the sides of the well and other portions engaging the .top I wall and means to fasten said top wall engaging portions to said chassis.

5. A tuner of the class described including a box like chassis having end walls and atop wall, a rotor rotatably mounted in said end walls and carrying tuner strips rotatable below the top wall and having contacts thereon, said top wall being formed with a shallow well disposed above said rotor and fixed contact carrying members secured in the bottom of said well and having fixed contacts arranged for engagement with the contacts on said rotor strips, means for closing said top well com,- prising a cover having portions entering into and engaging the sides of the well and other portions engaging the top wall, means to fasten said top wall engaging portions to said chassis, a transmission line having one end secured to at least a pair of said fixed contacts and ex tending out of said well, and said cover having a lug for engagement with the mid-portion of the line to press the line between the lug. and the edge of said well when the cover is secured in place.

. journaled in said end 6. A tuner of the class described including a chassis of box like form having a shallow well in the top thereof, a fixed contact supporting member secured to the bottom of said well and including a body of insulating material having rectangular openings formed therein, slots extending through said body disposed in spaced relation to the openings at one end thereof, and fixed contacts riveted to the body between the slots and the openings and each comprised of a strip of material formed to provide a curved body disposed in the corresponding rectangular opening and formed with a lug extending upward through the adjacent slot in the insulating body.

7. A tuner of the class described including a chassis of box like form having a shallow well in the top thereof, a fixed contact supporting member secured to the bottom of said well and including a material having rectangular openings formed therein, slots extending through said body disposed in spaced relation to the openings at one end thereof, fixed contacts riveted to the body between the slots and the openings and each comprised of a strip of material formedto provide a curved body disposed in the corresponding rectangular opening and formed with a lug extending upward through the adjacent slot in the insulating body, and a second lug extending below the insulating material.

8. A tuner of the class described comprising a box like chassis having oppositely disposed end walls, side walls and a top wall, a rotor for said tuner rotatably journalledin said end walls and carrying tuner strips with contacts thereon, said rotor being journaled closer to one side wall of the chassis than the other, tube sock ets mounted on the chassis toward the side wall having the greatest space from the rotor, said top wall being formed with a shallow well having one side deeper than t the other, and fixed contact blocks carrying fixed contacts supported on flanges carried by the sides of said well, said contact blocks being inclined relative to the top wall of the chassis and disposed in a plane normal to a diameter through the rotor and through the midportion of the fixed contacts.

9. A tuner of the class described comprising a box like chassis having oppositely disposed end walls, side walls and a top wall, a rotor for said tuner rotatably walls and carrying tuner strips with contacts thereon, said rotor being journaled closer to one side wall of the chassis than the other, tube sockets mounted on the chassis toward the side wall having the greatest space from the rotor, said top wall being formed with a shallow well having one side deeper than the other and fixed contact blocks carrying fixed contacts supported on flanges carried by the sides of said well, said contact blocks being inclined relative to the top wall of the chassis and disposed in a plane normal to a diameter through the rotor and through the mid portion of the fixed contacts, said deeper side of the well being provided with lead through openings to permit leads to be run therethrough and connected to said fixed contacts in said well.

10. A tuner of the class described including a chassis having at least a top wall and bearing supporting means for a rotor suspended from the top wall in oppositely spaced relation to each other, said top wall being formed with a well therein, fixed contacts mounted in said well in the top wall, a rotor supported by said bearing means, said rotor having supporting means for coil strips carried thereby and comprising disc like members having radially extending openings, said coil strips including coil supports of generally rectangular cross section supported in radially extending directions from said supports with the wider portion extending toward the axis of the rotor and the narrow portion extending circumferentially of the rotor.

ll. A coil strip for a tuner comprising a generally rectangular frame for supporting coils therein, said frame body of insulating including an outer bar of generally quadrilateral cross section, contact means carried by said frame for connection to said coils and comprising a thin metallic member wrapped around said frame with its ends meeting at one side of the frame and secured together to form a solder lug, at least one corner of said strip where it surrounds the frame being provided with a bight extending away from the corner to provide resilient means to hold the contact resiliently against the frames.

12. A television tuner comprising a chassis having a top wall, opposite end walls which extend down from the opposite ends of said top wall and opposite sides which extend down from said top wall between said end Walls, a rotor for said tuner rotatably journalled in said end walls and extending between said end walls below said top Wall, said rotor carrying tuner strips with contacts theron and being journalled in said end walls closer to one side of the chassis than to the opposite side, said top wall of chassis than to said opposite side and which overlies the rotor, insulation contact blocks mounted on the chassis at said opening in the top Wall, fixed contacts mounted on said blocks and facing downward therefrom for engagement by contacts on the rotor strips selectively as the rotor is turned, and tube sockets mounted on the chassis top wall between said opening therein and said opposite side of the chassis.

13. A television tuner comprising a chassis, an insulation block mounted on said chassis, said insulation block being formed with a plurality of openings therein and corresponding slots spaced from said openings at one end thereof, a plurality of contact strips mounted on said insulation block, each contact strip comprising a curved portion disposed at one of said openings in the block and projecting thereat beyond one face of the block, a fiat portion connected to said curved portion and extending across said one face of the block between said one end of the opening and the corresponding slot, and a lug connected to said flat portion and extending through said slot and beyond the opposite face of the block, rivets securing the flat portions of the contact strips to the block, a rotor rotatably mounted on the chassis in confronting relation to said one face of the block, tuning means on said rotor, and a plurality of contacts on the periphery of the rotor positioned to engage the curved portions of the contact strips on the block selectively depending upon the position to which the rotor is turned.

References Cited in the file of this patent UNITED STATES PATENTS 1,633,870 Potter June 28, 1927 1,983,680 Scofield Dec. 11, 1934 2,496,183 Thias Jan. 31, 1950 2,585,844 Romero Feb. 12, 1952 2,611,807 Lazzery Sept. 23, 1952 2,627,579 Waswansdortf Feb. 3, 1953 2,657,365 Lazzery Oct. 27, 1953 2,706,252 Overman Apr. 12, 1955 2,772,351 Machlin Nov. 27, 1956 2,772,354 Browder Nov. 27, 1956 

